Rutile was described as a mineral species by Werner in 1803, from specimens purportedly from "Cajuelo, Vuitrago, Burgos". It is clear that this was an error, and the actual locality for the specimens studied by Werner was Horcajuelo de la Sierra (Madrid), where their existence was already known as a curiosity, scientifically undefined, since well before. Consequently, Horcajuelo de la Sierra (Madrid) is the real type locality for this mineral. The cause of Werner's erroneous reference to Vuitrago (Buitrago) may have been the historical fact that Horcajuelo belonged to the Señorío de Buitrago, from the Duques del Infantado until the abolition of the residual feudal regime in 1830.